Study of Clostridioides Difficile in Infants

Inclusion Criteria: 1. Age Range: Infants aged 0 to 2 years (inclusive) at the time of sample collection or medical record documentation. 2. Data Availability: Complete medical records or available stool samples within the study's retrospective time frame. 3. Group-Specific Criteria: CDI Patients: Documented diarrhea or related gastrointestinal symptoms, with laboratory-confirmed C. difficile by PCR or culture. Asymptomatic Carriers: Positive C. difficile test (PCR or culture) in the absence of diarrhea or other clinical CDI symptoms. Healthy Controls: Negative C. difficile test and no gastrointestinal symptoms indicative of CDI. 4. Consent/Authorization:Retrospective data (e.g., existing medical records or stored biosamples) may be included under a waiver of consent if approved by the institutional review board (IRB). However, any new information obtained directly from participants or their guardians (e.g., via questionnaires) requires explicit informed consent. Exclusion Criteria: 1. Incomplete Data: Infants whose medical records lack sufficient information to confirm their CDI status or those without adequate stool sample results. 2. Ambiguous Diagnosis: Patients presenting with other infectious diseases or conditions that could not rule out alternative diagnoses for diarrhea (e.g., confirmed concurrent viral or parasitic infections) without conclusive C. difficile testing. 3. Severe Comorbidities: Infants with life-threatening congenital conditions (e.g., severe immunodeficiency syndromes) if these conditions significantly alter the gut microbiota or confound CDI diagnosis.